1. Technical Field
The present invention is related to an optical filter, an optical module, an electronic apparatus, and a method of manufacturing an optical filter.
2. Related Art
In the past, an optical filter has been utilized for selectively emitting light with a specific wavelength out of the incident light. Further, an optical filter for emitting light with a specific wavelength is disclosed in JP-A-2012-27224. According to JP-A-2012-27224, the optical filter has a pair of substrates opposed to each other, and reflecting films disposed on respective surfaces opposed to each other of these substrates. The optical filter has a structure having electrodes respectively disposed in the peripheries of these reflecting films, and at the same time having a diaphragm section disposed in the periphery of the reflecting film.
The optical filter is capable of selectively taking out light with a wavelength corresponding to a dimension of a gap between the pair of reflecting films opposed to each other. The gap between the reflecting films can be controlled to be a desired value (distance) using electrostatic drive by applying a voltage between a stationary electrode disposed on one of the substrates and a movable electrode disposed on the other of the substrates.
Optical filters can also be utilized in air containing moisture. Water molecules repeatedly collide with each other to become charged while moving in the air. When the water molecules thus charged adhere to the reflecting films, the reflecting films become charged. Then, a voltage difference occurs between the reflecting films opposed to each other, and thus an electrostatic force acts between the reflecting films. Thus, the distance between the reflecting films opposed to each other varies. Since the distance between the reflecting films affects the wavelength of the light to be transmitted through the optical filter, the wavelength of the light to be transmitted through the optical filter fluctuates if the distance between the reflecting films fluctuates. Therefore, there has been demanded an optical filter hardly fluctuating in the wavelength of the light to be transmitted through the optical filter, and a method of manufacturing such an optical filter with high productivity.